Push rod or similar device



Nov. 10, 1964 e. M. BEARDOW 3,156,806

PUSH ROD 0R SIMILAR DEVICE Filed March 6, 1963 my M i i k 4 /5 INVENTOR.

@0478 M. flea/dour I W ,qTTOE/VEYS United States Patent 3,156,806 PUSH RGD OR SIMILAR DEVKCE George M. Beardow, Redding Ridge, Conn, assignor to Vitramon, Incorporated, Monroe, Conn., a corporation of Delaware Filed Mar. 6, 1963, Ser. No. 263,253 7 Claims. (Cl. 200172) This invention relates to improved push rods and similar devices slidably mounted for reciprocation. More specifically, it pertains to push rods or similar operating members for high speed electrical switches or the like.

It is an important object of the present invention to provide an improved push rod or similar device, adapted to be slidably mounted for reciprocation, which is adapted to be operated at extremely high speeds, such, for example, as in the electrical switch disclosed in my United States Patent No. 2,993,963, is substantially self-lubricating and is capable of being impregnated with hardening resins, lubricants or similar materials.

It is also an object of the invention to provide a push rod or similar device which has high strength in a longitudinal direction, whereby relatively great force may be exerted by the rod as it is reciprocated, and is adapted to withstand continuous or intermittent stresses in a direction transverse to its axis, such as might be created by a cam or similar means engaging an end of the rod for reciprocating the same.

Another object of the invention is to provide a push rod or similar device, having characteristics of axial and transverse strength, uniformity of cross-section dimension throughout its length, being readily impregnated and self-lubricating, which may be turned out of natural stock, by quantity production means, in a wide range of sizes without substantially affecting its characteristics.

Still another object of the invention is to provide an improved rod construction for slidable reciprocation in a bore by forming the rod from an elongate body of natural, fibrous, cellulose material, such as bamboo, in which the fibers are all substantially straight and continuous throughout the length of the body and are parallel to the longitudinal axis thereof.

A further object of the invention is to provide an improved device, of the character wherein a rod is slidably reciprocated in a bore, by forming the rod of bamboo or similar fibrous, cellulose stock, in which the fibers lie parallel to the longitudinal axis of the stock and are substantially straight and continuous throughout its length.

Other objects and advantages of the invention will be apparent from the specification and claims, when considered in connection with the attached sheet of drawings, illustrating one form of the invention, wherein like characters represent like parts and in which:

FIGURE 1 is a fragmentary, elevational View, partially in section, of a device embodying the invention;

FIG. 2 is an elevational View, partially broken away and in section, of an electrical switch device embodying the invention; and

FIG. 3 is an enlarged perspective View of a section of fibrous, cellulose stock from which a push rod is formed, according to the invention.

Referring now to the drawings for a more detailed description of the invention, in FIG. 1 the essential elements of a push rod type operating mechanism, generally indicated by the numeral 14), are shown embodying the invention.

The mechanism it), which, in substance, is embodied in innumerable devices requiring a reciprocating operator for imparting movement thereto, comprises a push rod 11 slidably mounted for reciprocation in a bore 12, which may be formed in a frame or housing of the device to 14 of such device.

which the mechanism is connected or may, as here illustrated, be provided by a bushing 13 mounted in a portion Actuating means 15, which may take any known form, including that of the cam illustrated, are positioned operably adjacent an end of the rod 11 for imparting intermittent longitudinal movement thereto in one direction, while further means 16, preferably resilient, engage the opposite end of the rod for normally biasing it toward the actuating means and returning it to normal position to complete an actuating cycle.

While, heretofore, mechanisms 10 have functioned with reasonable success incorporating metal or similar type push rods, it has been found that when the push rod is operated at high speeds considerable wear on the push rod and the actuating means is encountered, particularly where the actuating means strikes the push rod transverse to its longitudinal axis, such as with the cam shown, and the end of the rod wipes across the surface of the actuating means. Attempts to overcome this problem by reducing the friction between the push rod and the actuating means, such as by the use of lubricants or known mechanical means, have proven either ineffective or too expensive.

The present invention, however, provides a solution to the problem by providing a push rod having natural characteristics of relatively great axial and transverse strength coupled with the advantages of self-lubrication and the capability of being impregnated.

According to the invention, the push rod 11 is formed from a unitary piece of natural, fibrous, cellulose stock 17 (see FIG. 3), such, for example, as bamboo or the like, in which substantially all of the fibers 18 thereof are straight and continuous throughout the length of the stock and are parallel to its longitudinal axis. It has been found that by utilizing such natural material in the manufacture of push rods, particularly for use in high speed devices, the inherent strength of its cellular structure, as seen at 19, together with the lubricating advantages of its natural oils produce a rod having the desired characteristics. Further, the cellular nature of the stock, as Well as the tubular nature of its fibers, enables the ultimate push rod to be impregnated with resins, lubricants or similar materials for purposes of hardening, insulating, lubricating or similarly treating the rod.

In choosing the fibrous, cellulose material for making the push rods, according to the invention, it is essential, as noted above, that substantially all of the fibers be straight and continuous throughout the length of,- at least, that portion of the body of the stock that is to be utilized for the rods, and that such fibers lie substantially parallel to the longitudinal axis of the body. The relationship and character of the fibers, in addition to providing the desired axial and transverse strength in the push rods, facilitate the manufacture of rods, in a relatively unlimited number of sizes and to very close tolerances, from the same base stock without a substantial reduction in the relative characteristics of the finished piece.

The push rods may be manufactured by turning the stock 17 down to the desired diameter on a lathe, by drawing it through a forming die, by a combination of turning and die forming or in anyother known manner, since the configuration and relationship of the fibers will always produce a finished product, wherein substantially all of the remaining fibers are unbroken and extend from one end of the rod to the other.

Referring now to FIG. 2 of the drawings, a push rod, according to the invention, is shown advantageously embodied in a high speed electrical switch device 20 of the type disclosed in-my United States Patent No. 2,993,963, to which reference may be made for particular details of construction.

As illustrated, the switch device 20 generally comprises an insulating housing 21 having a recess 22 therein into which one end of a stationary contact 23 projects, the contact being provided with a contact portion 24. The other end of the stationary contact is secured in the housing and has a terminal 25 projecting from the upper face of the housing. Cooperating with the stationary contact 23 is a movable contact member 26 of resilient material carried by the housing and connected to a terminal Z7 projecting from the upper face thereof. One end 26a of the movable contact extends into the recess 22 to lie adjacent the stationary or fixed contact 23 and is normally urged, by the resiliency of the material from which the movable contact is made, into closed circuit position with the contact portion While the resiliency of the movable contact itself is normally suflicient to bias it into closed circuit position with the stationary contact, in the illustrated form of the invention the resiliency of the movable contact is augmented by a spring 28, having one end fixed to the housing and the other end secured to the movable contact.

A retaining member 29 having one end embedded in or secured to the housing and the other end extending into the recess 7.2 in a position adjacent and below the movable contact, or at the side thereof opposite the stationary contact, has a contact engaging portion 39 adapted to overlie the movable contact. The retaining member, which is formed of resilient material, is normally urged to the position shown in FIG. 2 wherein the contact engaging portion 30 engages the end of the movable contact 25 and holds it, against its normal biasing force, in an open circuit position.

The switch incorporates a push rod type operating means that includes a plunger or push rod 31 having means in the form of a head 32 at the inner end thereof engaging the retaining member 2%. The push rod, which is made, in accordance with the present invention, of a natural, fibrous cellulose material in which substantially all of the fibers are straight, continuous throughout the length of the rod and parallel to the longitudinal axis thereof, is slidably mounted in a bore 33 provided by a tubular bearing or bushing 34 mounted in the housing. It will be noted that the push rod in normal position, which results from the resilient pressure of the retaining member 29 acting longitudinally against its inner end, extends a predetermined distance below the end of the bushing so that it is in position to be engaged by a cam 35 or similar actuating means.

In the operation of the switch, whether utilized singly or in combination with a plurality of other switch devices, such as in a commutator, the circuit between the contacts is closed when the push rod 31 is shifted inwardly, against the biasing force of the retaining member 29, by the actuatin means 35 so that the retaining member moves toward the stationary contact member 23 enabling the movable contact to engage the stationary contact. In accordance with the instant switch construction, as more fully disclosed in my Patent No. 2,993,963, continued inward movement of the push rod disengages the contact engaging portion 30 of the retaining member from the movable contact so that the closed contacts are free of any vibration that may be transmitted from the operating or actuating means of the switch. On removal of the actuating pressureagainst the push rod, such as might result from the completion of a camming operation, the rod is returned to normal position by the resiliency of the retaining member, thus breaking the contact between the movable and stationary contact members and opening the circuit.

The switch 29, which is adapted to produce up to 1000 switching cycles per second, as may be necessary in telemetering devices, digital computers or similar apparatus, and which may, as a result of its application be required to operate over a long period of time without evidencing wear requiring repair or replacement, uniquely illustrates the advantages of the present invention as embodied in the push rod 31. The strength of the push rod, resulting from its fibrous cellular construction, as well as its self-lubricating characteristics produces operating means capable of meeting the advanced and demanding requirements of modern technology. Similarly, the character and relationship of the fibers facilitate the relatively inexpensive manufacture of the push rods in large quantities and varying sizes within very close tolerances. 4

Thus, among others, the several objects and advantages of the invention as aforenoted are achieved. Obviously numerous changes in the structure may be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

1. In the combination of an elongate rod, means for slidably mounting said rod for longitudinal movement and means for reciprocating said rod; the improvement wherein said rod comprises a unitary bamboo body having substantially all of the fibers thereof straight and continuous throughout the length of the body, said fibers being parallel to the longitudinal axis of the body.

2. In the combination including an elongate rod, means for slidably reciprocably mounting said rod, means for longitudinally shifting the rod in one direction and means for shifting the rod in the opposite direction; the improvement wherein said rod comprises an elongate unitary natural fibrous cellulose body having the fibers thereof continuous 'hroughout their length and straight and paraliel to the longitudinal axis of the body.

3. In the combination including an elongate rod, means for slidably mounting said rod for longitudinal reciprocation, means movable transversely of the axis of said rod and intermittently engageable with an end thereof for longitudinally shifting said rod in one direction in said mounting means and means for longitudinally shifting said rod in the opposite direction; the improvement wherein said rod comprises a natural fibrous cellulose body having the fibers thereof substantially straight and longitudinaliy continuous throughout the length of said body, said fibers being parallel to the longitudinal axis of the body.

4. In an electrical switch including at least one fixed contact, a movable contact adapted to be moved into and out of engagement with said fixed contact and operating means for moving said movable contact, said operating means including a rod engageable with said movable contact and slidably mounted within a bore, and means for reciprocating said rod in said bore; the improvement in said operating means wherein said rod comprises an elongate natural fibrous cellulose body in which substantially all the fibers are straight and continuous throughout the length of the body and are parallel to the longitudinal axis of the body.

5. In an electrical switch including a fixed contact, a movable contact resiliently biased toward said fixed contact for making electrical engagement therewith, contact restraining means resiliently biased away from said fixed contact and releasably engageable with said movable contact for holding the latter out of engagement with said fixed contact and operating means for moving said rcstraining means toward said fixed contact so that said movable contact is enabled to engage said fixed contact and is thereafter disengaged from said restraining means, said operating means including a rod slidably mounted within a bore and having an end thereof connected with said restraining means for moving said restraining means toward said fixed contact and means operably engageable with the opposite end of said rod for intermittently longitudinally shifting said rod in said bore for moving said restraining means toward said fixed contact; the improvement in said operating means wherein said rod comprises an elongate natural fibrous cellulose body in which substantially all the fibers therein are straight and continuous throughout the length of the body and are parallel to the longitudinal axis of the body.

6. An electrical switch unit comprising an insulated housing having a stationary contact member and a movable contact member mounted thereon, said movable CO!" tact member being resiliently biased toward said stationary contact member into closed circuit position, a retaining member mounted on the housing separate from the movable contact member and having a contact-engaging portion overlying a part of the movable contact member to form the sole operating connection thereto for normally holding the movable contact member in open circuit position, and a reciprocable operating rod longitudinally slidably carried by the housing, said rod comprising an elongate natural fibrous cellulose body in which substantially all the fibers therein are straight and continuous throughout the length of the body and are parallel to the longitudinal axis of the body, said operating rod cooperating with said retaining member for moving said retaining member from said normal position toward an operated position, the movable contact member being pressed against said contact engaging portion of the retaining member until said contact member is in electrical engagement with the stationary contact member and held in closed circuit position therewith, said engagement being prior to completion of movement of the retaining member to operated position in which the contact-engaging portion is out of engagement with the movable contact member and the contacts are free of the retaining member, whereby the closed contacts are maintained closed and free of any vibration as may be transmitted by the retaining member.

7. An electrical switch as in claim 6, wherein said elongate natural fibrous cellulose body comprises natural bamboo.

References Cited in the file of this patent UNITED STATES PATENTS 434,016 Devlan Aug. 12, 1890 1,527,613 Thacher Feb. 24, 1925 1,606,747 Carter Nov. 16, 1926 1,771,108 Atwater July 22, 1930 1,827,737 Coolidge Oct. 20, 1931 2,993,963 Beardow July 25, 1961 

1. IN THE COMBINATION OF AN ELONGATE ROD, MEANS FOR SLIDABLY MOUNTING SAID ROD FOR LONGITUDIAL MOVEMENT AND MEANS FOR RECIPROCATING SAID ROD; THE IMPROVEMENT WHEREIN SAID ROD COMPRISES A UNITARY BAMBOO BODY HAVING SUBSTANTIALLY ALL OF THE FIBERS THEREOF STRAIGHT AND CONTINUOUS THROUGHOUT THE LENGTH OF THE BODY, SAID FIBERS BEING PARALLEL TO THE LONGITUDINAL AXIS OF THE BODY. 